Asphalt and method for producing same



Jan. 22, 1935. u. B. BRAY ETAL 1,988,715

ASPHALT'AND METHOD FOR PRODUCING SAME Filed Aug. '7, 1933 3 Sheets-Sheet1 DUCT/LIT) Wm AT 77F PENETRATION/4T 77F 5 5 PERCENT OIL IN BLEND BYWEIGH 7" PERCENT OIL IN BLEND BY WEIGHT E19. 3 Fig i ELTQ/G 4 TENSILESTIFEIVGTH- I50 45 so 55 60 4a 45 50 PEI? 051w" OIL INBLEND 5r WEIGHTPER c5/vr O/L 11v BLEND BVWE/GHT I N VEN TORS UL/P/C' 5. EPA) LAWTON5.55 KW/TH Jan. 22, 1935. I u. B. BRAY ET AL 1,988,715

ASPHALT AND METHOD FOR PRODUCING SAME" Filed Au 7, 1933 s Shets-Sh-eet 2Big. 5 [151.6

260 4 280 MELT/N6 POINT IN "E MELTING POINT/N "E I80 200 220 240 260 28050 35 55 70 MELT/N6 POINT/N E TEMPEEA TURE [N I-T INVENTORS AND ULRIC B.BRA).

BY LAWTON 5.5ECKWl-TH ATTORNEY Jan. 22, 1935.

u. B BRAY El AL ASPHALT AND METHOD FOR PRODUCING SAME 3 Sheets-Sheet 5Filed Aug. 7, 1953 hm m? no INVENTORS AND [/L R16 5. EPA) BLYAWTON EBEC/(PV/TH ATTORNEY Patented Jan. 22, 1935 UNITED STATES means PATENTOFFICE 1,988,115 ASPHALT AND METHOD FOR PRODUCING a. SAME ApplicationAugust '7, 1933, Serial No. 684,094

9 Claims.

The present invention relates to asphalts and to methods for theirproduction. I

It is well known that both steam refined and oxidized asphalt arecomposed of solid bitumens and oil. For the purpose of this discussion,the

term bitumen will be used to designate the por- -tion of the asphaltwhich is insoluble in liquid propane and the term oil or raw oil todesighate that portion of the asphalt which is soluble 10 in liquidpropane. The amount of oil present in the asphalt is related to severalphysical characteristics of the asphalt such as the melting point andpenetration. A'n asphalt having a low melting point usually containsconsiderable portions of oil, while one having a high melting pointindicates the presence of a small amount of oil. The occurrence of largeproportions of oil in high melting point air blown asphalt is notgenerally recognized but we have definitely established that suchasphalts contain a considerable amount of oil and can be removed byextraction with solvents or by distillation with the aid of steam orunder high vacuum.

We have discovered that if an air blown asphalt produced from apetroleum residue is separated as by means of solvents, for example,propane, or by distillation, into its oil and bitumen constituents andthe bitumen constituent is blended with a selected fraction of the oilconstituent and/or with other oils, asphalts may be produced havingdifferent characteristics from the original oxidized asphalt. Thus,-ifthe oil constituent of the original asphalt is replaced in any desiredproportion with more parafiinic fractions of the propane extracted oilor with other parafiinic or saturated type oils, the blended asphaltwill exhibit a higher penetration at 77 F. for the same melting pointand a relatively lower susceptibility to temperature change than theoriginal oxidized asphalt. A

40 blended asphalt of this type ismore useful as a battery sealingcompound or roofing cement than the oxidized asphalt from which it hasbeen produced. On the other hand, if the oil constituent of the oxidizedasphalt is replaced in any desired proportion with the more aromaticfractions of the extracted oil or with other aromatic type oils,

5 ordinarily employedin the manufacture of paints and storage batteryboxes. The asphalts mentioned herein and forming the subject of ourinsynthesized asphalts which are suitable for saturating felts andfabrics where it is desirable that 15 the asphalt have a highersusceptibility to temperature change. Other objects and advantages ofour invention will be apparent from the following description of ourinvention taken from the drawings.

Figs. 1 to 8, inclusive, represent characteristics of the compositeasphalt produced by our invention as compared with oxidized asphalt.

Fig. 9 is a schematic arrangement of apparatus for carrying out oneembodiment of our invention.

Briefly, the asphalts forming the subject of our invention may beproduced by first oxidizing a petroleum residuum or topped crude withair or other oxidizing gases to any desired melting point, for example,200 F. The oxidation will reduce the penetration and ductility of theasphalt. The oxidized asphalt is then er steam distilled under highvacuum to remove approximately onethird of the asphalt as an overheadfraction as an oil, or it may be mixed with a solvent capable ofdissolving the oil constituents of the asphalt and precipitate thebitumen. Solvents capable of effecting this are liquefied normallygaseous hydrocarbon solvents as ethane, propanabutane, 4o iso-butane ormixtures thereof. Such hydrocarbon solvents are obtained byrectification of casinghead gasoline by the so-called stabilizing methodnow conventional in the natural gasoline industry. They comprise theoverhead gaseous fractions of the stabilizing process. The gaseousfractions are liquefied by compression and cooling in the conventionalmanner and are drawn of! into pressure chambers where they aremaintained in the liquid state until they are used. A so typicalanalysis of such a fraction is 6.72% ethane, 72.2% propane, 19.91%iso-butane and 1.17% normal butane. The necessary pressure to maintainthis fraction in a liquid state is approximately 125 lbs. per sq. in.gauge at 75 F. In the presthat is, reduce its viscosity, with a solventwhich is liquid at normal temperatures and pressures. Such solvents maycomprise naphtha, benzol and mineral spirits having a boiling range of300 F.

to 400 F. This will facilitate subsequent contact of the oil with thelighter solvent, i. e. propane.

The benzol solution having the consistency of a heavy road oil may thenbe extracted with approximately 300 to 500 volume percent of the liquidpropane under pressure suflicient to maintain the propane liquid atatmospheric temperature. The propane phase of the extraction is thendecanted and distilled to remove propane and benzol from the oilremaining as still bottoms. This oil maybe further extracted with morepropane to precipitate bitumen which has been carried over into thepropane layerbecause of the presence of the benzol in the primaryextraction. The bitumen phase'from the primary extraction may be furtherwashed with a fresh charge of propane to remove any unseparated oilsfrom the first extraction. The washed bitumen is mixed with a smallquantity of additional bitumen precipitated in the re-extraction of theoil. The oil recovered in the rewashing of the bitumen is mixed with theoil of the primary extraction. If the oil separated from the asphaltcontains wax this may be separated by refrigeration and settling orfiltration.

The oil is then separated by means of a selective solvent, such asliquid sulfur dioxide, into an'oil having a low gravity viscosityconstant, i. e. low-temperature viscosity susceptibility and one havinga high gravity viscosity constant, that is, a high temperature viscositysusceptibility. The oils having a low gravity viscosity constant arethose resembling Eastern or paraflin base oils or saturated type oils,while oils of high gravity viscosity constants are those of the aromatictype. The gravity viscosity constant has been definedby Hill and Coatesin the Journal of Ind. and Eng.

Gulf Coast type to .807 for an Eastern Pennsyl-' Vania type or evenbeyond. As solvents which will effect the separation of the oil into thetwo types, we have found liquid sulphur dioxide, mixtures of liquidsulphur dioxide and benzol, mixtures of acetone and benzol,chloraniline, nitrobenzene, furfurol, phenol, aniline or methyl formateuseful. Nitrobenzene or chloraniline alone, in addition to being anasphalt precipitant, also has, in some measure, the ability to split theoil in the above manner. Liquid sulphur dioxide has been foundespecially valuable as a solvent to separate the propane extract intooils having a low viscosity gravity constant, this oil being commonlyknown as the raflinate and an oil having high viscosity gravity constantwhich is known as the -extract. The. rafiinate may be furthersuccessively treated with fresh liquid sulphur dioxide to produce asecond extract and also a third extract.

The characteristics of the oils thus extracted and the raflinate may beviewed from an inspection of Table 1.

Table 1.--E.rtraction data from liquid sulphur dioxide treatment of rawoil separated from oxidized asphalt and physical and chemical tests onthe raw oil, extracts and rajfinate oils treatment data Physical tests Pisgos- V er- 1 y ay- 18- 011 Vol. cent Grew bolt cosity Aniperscgpt byhtity Unl-l grgvlinet o a weig versa 1 y pom used ofraw insecs. con- C.

oil at stant Raw oil None. 100 18.1 131.5 .876 75.5 First extract 0-30020.3 11.5 191 .926 33.0 Second extract 8.7 12.8 .916 42.0 Third extract600-900 5. 8 14. 2 146 908 52. 5 Final raflinate 900 65.2 20.7 129.5.855 92.5

Chemical tests Ultimate analysis, percent Proxirnate analysis.

by weight percent by volume on Other t??? or y Un- Aro- S C H Nsatumatgg rep rates ics 100 ence percent Raw oil 2.39 85.0 11.5 0.300.81 26.8 26.0 47.2 First extract 3.74 83.5 10.8 0. 36 1.60 37.6 44.018.4 Second extract... 3. 54 85.6 10.6 0.38 0.l2 34.0 48.4 17.6 Thirdextract--. 3.15 83.5 11.4, 0.33 1.62 26.0 38.0 36.0 Final raflinate.-1.76 83.6 12.5 0.16 1.88 5.6 14.0 80.4

The extracts and final raflinate shown in the table were blended invarious proportions with the bitumen separated by means of liquidpropane from the oxidized asphalt. However, since the first and secondextracts and final rafflnate shows the greatest divergence incharacteristics from the original oil, only these constituents wereblended with the bitumen in various proportions.

Blends were not made with the third extract on account of the smallyields of this material and less marked dissimilarity from the originaloil. The blends of bitumen with the extract covered the range of 45% to54% oil, while those of raffinate covered the range of 45% to 66% oil.The various tests on' these blends are given in Figs. 1 to 8, inclusive.Figs. 1 to 4, inclusive, show the variation in ductilitmpenetration,tensile strength and melting point by the variation in amounts of theoils in the mixture. Figs. 5, 6 and 7 show the variation in penetration,ductility and tensile strength by variation of melting point of thevarious blends, while Fig. 8 is a plot showing the temperaturesusceptibility of ductility of the various blends. It will be observedthat the blends of extracts and raffinate with bitumen are compared witha blend ofthe raw oil with the bitumen, the raw oil comprising thepropane soluble portion of the original oxidized asphalt and from whichthe extracts and raflinate were produced. It may be stated that theblends of raw oil and bitumen correspond veryv closely in physicalproperties to ordinary air-blown asphalts of equal at which the originalasphalt becomes sufiiciently brittle to crack or chip quite easily.

melting point produced by direct air blowing of the same residuumemployed in the manufacture of the asphalt subjected to propaneextraction.

It will be observed by reference to Fig. 1 that for any given percentageof oil, the blends of bitumen with sulphur dioxide soluble extracts havehigher ductilities than blends with the raffinate, with the blends ofraw oil falling in between. However, it will be noted from Fig. 3 thatblending with the extract gives the lowest melting point and blendingwith the rafiinate the highest for any given percentage of oil so thatwhen blends oi equal melting point are compared as in Fig. 5, it will beobserved that the extracts give superior ductilities only for blendshaving a lower melting point, e. g. 210 F. than the original asphalt.For meltingpoints above that of the original asphalt, the blends ofrafiinate with bitumen are highest, while those with extracts are lowestin ductility fora given melting point.

Considering the susceptibility of ductility to change in temperature forasphalt of approximate equal melting points, it is seen from Fig. 8 thatwhile blends of bitumen and sulphur dioxide extract are high inductility at 77 F., they exhibit an exceedingly high rate of change inductility with temperature so "that the asphalts of this variety with arelatively high ductility at 77 F.

show markedly less ductility at temperatures below 60 F. On the otherhand, a blend with rafilnate shows the lowest rate of change inductility with temperature, while those with raw oil are intermediate aswould be expected. It will be observed in Fig. 8 that curves 0 and 0'represent the change in ductility of asphalts composed of raw oil andbitumen, the asphalts having melt-.

ing points of 188 F. and 207 F., respectively. Curves E, E and E"representmixtures of extract and bitumen, the mixtures having meltingpoints of 182 F., 189 F. and 216 F., respectively. Curves R, R and R"represent mixtures of raflinate and bitumen, the mixtures having meltingpoints of 196 F., 213 F. and 230 F., respectively. To the best of ourknowledge, the low rates of change of ductility with temperature for theblends composed of raflinate and bitumen represent a markedimprovementover naturally occurring asphalts or those produced by theusual methods. The advantages possessed by an asphalt which showspractically no change in duetility and lack of brittleness over thetemperature range from approximately 30 to F. are obvious.

Thus, for ductility at 77 F. higher values are obtained for a givenmelting point by blending the sulphur dioxide extract with bitumen untila melting point corresponding roughly to that of the original asphalt isreached, e. g. melting point of 210 F. For melting points higher thanthis temperature, e. g. 210 F., the higher values are obtained byblending the rallinate with the bitumen. To produce asphalt which willshow the minimum of change in ductility with tem perature, the bestresults are obtained by blending raflinate with bitumen. By solventextracting the original asphalt, subjecting the thus separated oil toEdeleanu treatment, rejecting the extract portions and blending theraflinate with the bitumen, no appreciable change in ductility at 77 F.for the same melting point is obtained as compared to the originalasphalt but the susceptibility of the ductility to temperature change isvery greatly reduced. The asphalt in this manner will exhibitconsiderable ductility or lack of brittleness far below that temperatureBy reference to Fig. 2, it will be observed that the penetration at 77F. for the various blends of the diiferent oils with the bitumen happensto be the same for the same percent of any of the oils in the blend sothat the penetration at 77 F. is dependent only on the percentage of oilin the blend and not upon its treatment after propane extraction.

However, the melting point of the blend corresponding to a givenpercentage of oil is not independent of the nature of the oil but thereisconsiderable variation in melting point for the same percentage ofblends of extract, raw oil and raffinate. Thus, by referring to Fig. 6and considering penetration for any given melting point, it is evidentthat the raifinate blends have the highest penetration and the extractblends the lowest with the raw oil'blend falling in between. This is theequivalent of saying that for a given penetration the raflinate blendshave the highezt melting points and the extract blends the 'lowestmelting points. When classified by the usual melting point andpenetration relation, the blends of. raflin'ate and bitumen show moreair blown characteristics than the still run asphalts, while the extractblends tend to show more steam blown characteristics.

While the theory involved in these phenomena is not establisheddefinitely, we believe that the reason for the peculiar behavior of theraflinate blends for a given melting point is that the state ofdispersionof the bitumen in the raifinate blends is distinctly differentfrom that in the extract blends, the raffinate being a relativelysaturated and non-aromatic oil is not as good an asphalt solvent as theunsaturated and aromatic extracts. The result is that the railinateblends carry the asphalt in a dispersed or emulsified state as well asin true solution, while the extract blends are probably more homogenousand more nearly approximate a true solution of asphalt in oil. Thisapparent two-phase structure of raffinate blends is probably influentialin giving them a low susceptibility factor, while the low viscositytemperature susceptibility or low gravity viscosity constant of the,ra-flinate oil itself is also probably a factor. In fact, the rafiinateblends are thought to represent quantitatively an asphalt withexaggerated air blown characteristics.

Thus, it appears that for a given percentage of oil blended with thepropane insoluble bitumen, the penetration of the blend at 77 F. happensto be independent of whether the oil taken is the extract, raw oil orrafinate. For a given melting point, however, the nature of the oiltaken has a very marked influence upon the penetration at 77 F. becausethe melting point for a given percentage of oil varies markedly forraifinate, raw oil and extract. For a given melting point, the blends ofbitumen with raftinate show the highest penetrations and the blends withextract the lowest with blends of raw oil and bitumen falling inbetween. For a given penetration at 77 F. corresponding to equalpercentages of the different classes of oils, the mel ing points aredifferent, the raflinate bends exhibiting the highest point and theextract blends the lowest. The higher penetration for a given meltingpoint or a higher melting point for a given penetration for therafiinate blends as compared to the blends of extract and states ofdispersion of the bitumen in the raffinate. The physical tests of theraflinate blends represent exaggerated air blown characteristics and arethought to be due to the existence of two or more phases in air blownasphalt rather than one homogenous phase.

The tensile strength of asphalt is a property which is not usuallydetermined but is, of course, of considerable importance in theselection of an asphalt for particular purposes, such as in themanufacture of sewer joint compounds and moulded plastics. The tensilestrength of asphalt is measured by pulling apart in a suitable tensilestrength testing machine and noting the force required to pull apart theordinary ductility briquet of one square centimeter cross-sectional areaat the narrowest point. Considering tensile strength as a function ofpercentage of oil in the blend, the variation in tensile strengthbetween the blends of the different classes of oil may be viewed from aninspection of Fig. 3. However, these results may possibly be misleadingbecause of the variation in melting point between the blends of thedifferent classes of oil for a given percentage of oil. By inspectingFig. 7 where the tensile strength has been plotted as a function of themelting point, it will be observed that the extract blends are highestin tensile strength and the rafilnate blends are lowest in tensilestrength with the raw oil blends falling in between. The lower tensilestrength of the rafiinate blends is thought to be due to the dispersedor two-phased nature of these blends as compared to the more homogenousextract blends. The raflinate blends are more rubbery in character thanthe extract blends and they have a slightly dull luster as compared tothe bright luster of the extract blends. Thus, the extract blends arehigher in tensile strength than the raffinate blends with the blends ofraw oil and bitumen falling in between and this difference is believedto be due.

to the difference in state ofdispersion of the blends.

From the above discussion of our invention, it is apparent that anydesired types 01' asphalt may be produced by the proper combination ofmillnate or extract with bitumen. However, it will be observed that thisinvention is not to be limited by recomposition of the rafilnate orextract with the bitumen produced from the raw oil separated from thebitumen sinceraflinates and extracts of other oils or fractions of crudeoil having other gravities, viscosities and viscosity gravity constantsthan those indicated in Tablel may be substituted for those indicatedabove. Furthermore, other types of oils resembling the rafflnate such assaturated type blending agents may be substituted forthe rafllnate. Asexamples of such oils, we may employ acid tfeated Western oils, such aslubricating oils or solvent treated Western oils or lubricating oilssuch as those produced by treatment with liquid sulphur dioxide,mid-continent or Eastern oils of paraflin base or petrolatum.. Likewise,the extract for blending with the bitumen may be substituted by otheroils resembling the extract in composition. Such oils are the aromatictype blending agents. As examples of such oils, we may employ the liquidsulphur dioxide extracts from Western oils or mid-continent orPennsylvania. lubricating oil stock or any kind of lubricating oil stockhaving a gravity ofsay lower than 15 A. P. 1. Such oils having gravityof less than 15 A. P. I. are more aromatic than those above thisgravity. We may also employ coal-tar or coal tar distillates,

cracked petroleum oils or residues or the polymers resulting from theGray process, that is, the polymers resulting from treating crackedgasoline in the'vapor phase with clay. The blends of oil with thebitumen may be further air blown to bring the blend to the desiredspecification as to melting point or other characteristics.

The above discussion has been made with great particularity with respectto the separation of oil from the bitumen by means of solvents. However,we do not wish to be limited to this exact procedure since the oilconstituents of the oxidized asphalt may be separated by distillationunder high vacuum and the voil recovered may be extracted to produce araflinate and an extract in accordance with the above procedure and theseparated constituents then recomposed with the bitumen in any desiredproportion of the distillate may be discarded or employedas crackingstock and replaced by other type of oils mentioned above. As an example,we have produced a battery sealing compound by distilling approximatelyone-third of the oxidized asphalt and blending approximately parts byweight of the bottoms to 70 parts of an acid treated heavy Westernlubricating oil and further air blowing the composite asphalt.

It will be observed that for determining the melting or softening point,penetration, ductility and flash point, the following methods outlinedby the American Society of Testing Materials were used:

Softening or melting point; ball and ring method D36-26 PenetrationD5-25 Ductility D113-32T Flash point, Cleveland open cup method D-92-24The blended or composite asphalts hereinabove described may be producedby the following method:

Referring to Fig. 9, a topped crude oil, such as fuel oil having agravityof 14 A. P. I. and a viscosity of 100 seconds furol at122 F. istaken from tank 1 and passed into line 2 controlled by valve 3 andpumped by pump'4 into an oxidizing still 5 set in furnace 6 and heatedby burners 7. The stillis provided with perforated line 8 controlled byvalve 9 for introduction of air into the still. The light hydrocarbons,fixed gases and excess air from the still 5 pass through mist extractor10 and are removed from the still through line 11, condensed .incondenser 12 and the condensate and uncondensed gases are then passedthrough line 14 into run-down tank 15. Fixed gases an excess air arevented through line 16.

The oxidation in still 15 of the fuel oil is carried on until a test ofthe asphalt shows the desired characteristics, as for example, a meltingpoint of approximately 200 F., a penetration at 77 F. of approximately15, a ductility of 2 cm. at 77 F. and of 0 at 32 F. and a flash point ofapproximately 430 F.

Upon completion of the oxidation in still 5, the oxidized asphalt iswithdrawn via line 17, controlled by valve 18 and pumped by means ofpump 19 into line 20 where it is mixed with a liquid hydrocarbon solventsuch as benzol taken from tank 21 and introduced into line 20 via line22 controlled by valve 23 and pump 24. Approximately by weight of thesolvent is mixed with the asphalt for the purpose of cutting the asphaltback or reducing its viscosity and to thus facilitate contacting in thesubsequent admixture with liquid propane.

The asphalt and benzol is passed through turbulence coil for the purposeof effecting intimate admixture of the solvent with the asphalt. Thebenzol solution of asphalt having the consistency of a heavy road oil isthen passed into line 26 where it meets a stream of liquid propane takenfrom propane storage tank 27 via line 28' controlled by valve 29 andpump 30. Approximately three volumes of propane is mixed with one of thebenzol-asphalt mixture. ,The propane may contain 30% ethane. The mixtureis then passed through turbulence coil 31 for the purpose of effectingintimate admixture and then passed intothe extractor or settling tank32. In the extractor 32, a stratification of the mixture takes placeinto two layers, a lower layer consisting of bitumen and solvent and anupper layer of oil, benzol and propane. A pressure of approximately 125lbs. per sq. in. gauge is maintained in tank 32 for the purpose ofmaintaining the propane in a liquid state during extraction. Equilibriumline 33 controlled by valve 34 connects the extractor with propanestorage tank 27 also maintained at the aforesaid pressure. The bitumenphase settling to the bottom of tank 32 iswithdrawn via line 35controlled by valve 36 and passed to pump 37 which forces the bitumenthrough heating coil 38 where its temperature is raised to effectvaporization of entrained solvent. The heated mixture is then passed vialine 39 controlled by valve 40 into evaporator 41. Additional heat issupplied in evaporator 41 through closed steam coil 42. In evaporator41, the vaporized solvent is passed through mist extractor 43 into line44 controlled by valve 44' and thence through cooler 45 into separator46. Condensed light oils and benzol are withdrawn via line 47 while theuncondensed propane passes via line 48 into line 49-to the suction ofcompressor 50 where its pressure is raised to that of the high pressuresystem, i. e. approximately 125 lbs. per sq. in. gauge, liquefied incooler 51 and then passed into the propane storage tank 27. The bitumenis taken from the bottom of the evaporator 41 via line 52 controlled byvalve 52' and pumped into tank 54 by pump 53. The supernatant solutionof oil, propane and benzol is decanted from tank 32 and then passed tosuitable apparatus for the separation of propane. The oil-benzol.mixture is then subjected to refining with liquid sulphur dioxidehereinafter described.

However, if the original oil contained wax, it is preferable to removethis wax prior to the refining step. In this case, the supernatantsolution of oil, benzol and propane is decanted from the extractor 32and passed into line 55 by means of pump 56 which forces the mixturethrough valve 57 into chiller 58 maintained at a low pressure. Inchilling column 53, sufficient propane vaporizes to reduce thetemperature of the remaining material to a predetermined dewaxingtemperature which causes the wax to precipitate from solution. Thedesired dewaxing temperature is obtained by controlling the pressure incolumn 58 by the proper operation of valve on line 59 and compressor 50which is connected to the evaporator by lines 59 and 49. The pressure tobe maintained in column 58 will generally be about 0 lbs. gauge whichcorresponds to a temperature of approximately -40 F. As the propanesolution passes through valve 5'? its pressure is reduced so that aportion of the propane evaporates in the column 58 and the vapors passout of the top through line 59 controlled by valves 60 then through line49 to the suction of compressor 50 where the vapors are liquefied,cooled in 51 and passed to the propane storage tank 9. The chilled oildissolved in the propane and benzol carrying the precipitated wax isremoved from the chilling column 58 through line 61 controlled by valve62 by pump 63 which forces it into vapor-tight wax separator or settler64. In order to prevent ebullition or boiling in the wax separatorduring wax settling operation, pressure 'is imposed upon the solution ofoil. This is accompiished by maintaining pressure within theseparator bypump 63. As the chilled mass in separator 64 remains in a non-ebullientstate, the wax settles out and is collected by vanes 65 operated by belt66 connected to a suitable source of power not shown. The precipitatedwax slurry containins propane settling at the bottom of the waxseparator 64 is removed from the separator through line 68 controlled byvalve 69 and pump 70 which forces the slurry through heating coil '71where its temperature is raised to vaporize residual propane and is thenpassed into separator 72. Vaporized propane is passed to propane storagetank 27 via line '73 controlled by valve 74, compressor 50 and cooler51. The propane-free wax is withdrawn from the separator via linecontrolled by valve '76 and pump '77 into storage tank 78.

The chilled oil dissolved in propane and benzol and freed from wax iswithdrawn from the vaportight separator 64 via line by means of pump 81which forces the mixture through valve '82 into evaporator 83. Heat issupplied for vaporizing the propane by closed steam coil 84. Thevaporized propane passes through mist extractor 85 into line 86controlled by valve 87, cooled in cooler 88 and is then passed intoseparator 89in which any condensed naphtha and light oil which wasvaporized together with the propane in the evaporator 83 is withdrawnvia line 90, while the vaporized propane passes into line 91 and theninto line 49 to compressor 50, cooler 51 into propane storage tank 27.

The propane-free oil containing the heavier solvent, i. e. benzol, isremoved from evaporator 83 via line 92 controlled by valve 92' andpumped by pump 93 into line 94 and passed through cooler 95 where thetemperature of the mixture is lowered sufiiciently, i. e. toapproximately 10 F. for subsequent'extraction with liquid sulphurdioxide. It is preferable to add further quantities of benzol to the oilso as to make the proportions of benzol to oil equal. duced into line 94by means of line 79 controlled by valve 79'. The cooled oil from cooler95 passes by means of line 96 into the lower zone of extraction column97. Liquid sulphur dioxide from storage tank 98 passes into line 99controlled by valve 99' and pumped by pump 100 into the upper zone ofextraction column 9'7. Due to the difference in the specific gravity ofthe oil introduced into the lower zone of the extraction column and theliquid sulphur dioxide introduced into the upper zone of the extractioncolumn, these two liquids tend to separate. As the liquid sulphurdioxide passes down through the ascending column of oil,

it dissolves certain components present. This solution of oil in theliquid sulphur dioxide is removed by means of line 102 controlled byvalve The additional benzol may be intro-' pressed and sent by means ofline 111 to condenser 112 where it is liquefied and then by means ofline 114 to sulphur dioxide storage tank 98. The sulphur dioxide freeoil or extract containing benzol in evaporator 104 is removed throughline 115 controlled by valve 116 and sent by means of pump 117 tostorage tank 118.

The ascending column of oil in the extraction column 97 passes into line119 controlled by valve 120 into auxiliary separator 121 where anyremaining liquid sulphur dioxide is separated out and passes into line122 controlled by valve 123 and line 103 into evaporator 104. The clearoil in the auxiliary separator 121 is removed through line 124 and ispassed to evaporator 125 provided with mist extractor 126 where thesulphur dioxide present is vaporized with the aid of steam circulatedthrough closed coil 127. The sulphur dioxide vapor is removed from theevaporator 125 by means of line 128 controlled by valve 129 and sent bymeans of line 109 to compressor 110 where it is compressed and passes bymeans of line 111 to condenser 112 where it is liquefied and thencethrough line 114 to the sulphur dioxide storage tank 98. The sulphurdioxide free oil or rafiinate containing benzol in evaporator 125 ispassed by means of line 130 controlled by valve 131 and is pumped bypump 132 into storage tank 133.

The foregoing discussion relative to the separation of the oil free fromwax into an extract and raifinate by means of liquid sulphur dioxide hasbeen described as being effected in the presence of the benzol which wasoriginally introduced into the oxidized asphalt from storage tank 21. Inother words, we have purposely retained the benzol in the oil inevaporator 83 and then added further quantities of benzol via line 79 sothat the subsequent treatment with liquid sulphur dioxide may befacilitated. However, if desired, the benzol may be removed entirelyfrom the dewaxed oil by means of the heat introduced in evaporator 83and this solvent condensed and collected at the bottom of separator 89.The subsequent extraction of the oil may then be efiected in thepresence of equal volumes of other solvents, such as mineral spirits,boiling between 300 and 400 F. and introduced into the oil via line 79.It will be further observed that the rafilnate or refined oil collectingin storage tank 133 and the extract col- '-lected in storage tank 118will contain the heavier solvent. These oils may be steam topped ,atapproximately 350 F. to remove the solvent prior to blending with thebitumen as will be hereinafter described. However, if desired, theadmixture with the bitumen with either therafflnate or extract may beeffected in the presence of the solvent and then the mixturesteam-topped to remove the solvent prior to additional oxidation to bedescribed.

In order to effect blending with the bitumen, the latter is withdrawnfrom tank 54 by means of line 134 controlled by valve 135 and pumped bypump 136 through heater 137 into lines 138 and 139 where it may be mixedwith the rafiinate from tank 133 introduced into line 139 via line 140controlled by valve 141 and pump 142 or with the extract from tank 118introduced into the bitumen by means of line 143 controlled by valve 144and pump 145. Either mixture is then passed via line 146 into anauxiliary oxidizing still 147 set in furnace 148 and heated by burners149. Air or otheroxidizing gas is introduced into the still viaperforated line 150 controlled by valve 151. Light oils, fixed gases andexcess air are removed through mist extractor 152 and pass into line153,

thence through condenser 154, into line 155 and then into run-down tank156. Fixed gases and air are vented through 157. The oxidation iscarried on in still 147 until the admixture is brought to a properspecification whereupon it is removed from the still via line 158controlled by valve 159 and pumped by pump 160 into storage tank 161.

The above description of the process has been made with reference to theblending of the bitumen with either the raiflnate or extract producedfrom the original oxidized asphalt. If desired, and depending upon theamount of oil required in mixture to give a composite asphalt of desiredspecification as to melting point, penetration and ductility, additionalquantities of the same blending oil may be introduced into the bitumenfrom storage tank 162 withdrawn via line 163 controlled by valve 164 andpumped by pump 165 into line 139. If desired, the blending oil fromeither tanks 118 or 133 may be supplemented or replaced by other oil ofdesired character maintained in tank 162.

The amount and character of the oil blended with the bitumen will dependupon the uses to which composite asphalt are to be put and upon thecharacteristics desired of the asphalt.

If desired, the blends of bitumen with raifinate, extract or extraneousoils may not be subjected to further oxidation as in still 147 and maybe employed without any further treatment. By closing valve 146' andopening valve 166 on line 167 the blend may be passed to storage tank168.

As an alternative method for producing a battery sealing compound orroofing cement, an oil oxidized into asphalt to approximately 200 F.melting point, a penetration of 15 at 77 F. and a ductility of 2 cm. at77 F. and of 0 at 32 F. and having a flash point of approximately 430 F.may be distilled by steam distillation to remove approximately 30% ofthe oil and to leave hard bottoms of about 300 F. melting point.Approximately 30 parts by weight of the bottoms may be blended withapproximately 70 parts of oil of the saturated type such as the ramnateproduced by liquid sulphur dioxide extraction of the removed oil or ofother oils or an acid treated Western heavy lubricating oil having aflash point of approximately 375 to 425 F. and a viscosity of 800 to2000 seconds Saybolt Universal at 100 F. or a high flash pointlubricating oil produced from a mid-continent or eastern crude ofparafiln base or petrolatum, The blend of the bitumen or bottoms and thesaturated type oil may then be blown additionally with air and steam toproduce a synthesized asphalt having a melting point of 200 F., apenetration of 65 at 77 F., a ductility of 2 /2 cm. and 2 cm.,respectively, at 77 F. and 32 F. and a flash point of 500 F. It will beobserved that the penetration at 77 F. and the ductility 'at 32 13. havebeen increased considerably over the same tests on the original oxidizedasphalt and the composite asphalt is more suitable as a battery sealingcompound due to these increased properties than the original oxidizedasphalt.

The foregoing exemplary description is merely illustrative of preferredmodes of carrying out our invention and is not to be taken as limitingas many variations may be made within the scope of the following claimsby a person skilled in the artwithout departing from the spirit thereof.

We claim:---

1. A process for producing asphalt which comprises oxidizing an oil toproduce an oxidized asphalt, separating said oxidized asphalt into anoil fraction and a bitumen fraction substantially free from oil an dcommingling said bitumen fraction with oil of lower gravity viscositycontent than said separated oil.

2. A process for producing asphalt which comprises oxidizing an oil toproduce an oxidized asphalt, separating said oxidized oil into itsbitumen and oil constituents by means of solvents and blending saidseparated bitumen with oil having a lower gravity viscosity constantthan the oil originally present in said oxidized asphalt.

3. A process for producing asphalt which comprises oxidizing an oil toproduce an oxidized asphalt, separating said oxidized oil into an oilfraction and a bitumen fraction substantially free from oil by means ofdistillation and blending said separated bitumen with oil having a lowergravity viscosity constant than the oil originally present in saidoxidized asphalt.

4. A process for producing asphalt which comprises subjecting anasphaltic residual oil to oxidation with air to produce an oxidizedasphalt, commingling said oxidized asphalt with a solvent capable ofdissolving the oil constituent of said oxidized asphalt and toprecipitate its bitumen constituent, separating the oil solvent solutionfrom the bitumen, commingling said bitunien with an oil of lower gravityviscosity constant than the oil separated by said solvent and oxidizingsaid mixture. I

5. A process for producing asphalt which comprises subjecting anasphaltic residual oil to oxidation with air to produce an oxidizedasphalt, com-,

mingling said"oxidized oil with e liquefied normally gaseous hydrocarbonsolvent under pressure to separate said oxidized asphalt into its oilandbitumen constituents, commingling the oil constituent with a solventcapable of separating said oil into an oil having a low gravityviscosity constant and an oil having a high gravity viscosity constant,separating said oils from eachother and commingling said oil having alow gravity viscosity constant with said bitumen and subjecting saidmixture to further oxidation.

6. A process for producing asphalt which comprises subjecting anasphaltic residual oil to oxidation with air to produce an oxidizedasphalt,

separating said oxidized asphalt into its oil and bitumen constituentsby means of solvents, commingling its oil constituent with liquidsulphur dioxide to form an extract and a raflinate, commingling saidrailinate with said bitumen constituent and subjecting said mixture tofurther 7. A process for producing asphalt which comprises subjecting anasphaltic residual oil to oxidation with air to produce an oxidizedasphalt,

separating said oxidized asphalt into its oil and bitumen constituentsby means of liquid propane, separating said oil constituent into an oilhaving a low gravity viscosity constantand an oil having a highgravityviscosity constant, commingling said oil having a low gravityviscosity constant and said bitumen and adding to said mixture oils oflower gravity viscosity constant-than the oil constituents separatedfrom said oxidized asphalt.

8. A composite asphalt produced from an oxidized asphalt in which theoil constituent of the oxidized asphalt has en replaced with oil ofhigher paraiflnicity, 5 id composite asphalt having a higher penetrationat 77 F. for the same melting point and a, higher ductility at 77- F.for melting points above 210 F. than said oxidized asphalt.

9. A composite asphalt produced from oxidized asphalt in which the oilconstituent of the oxidized asphalt has been replaced with oil of higherparaflinicity, said composite asphalt having a lower ductility, at 77F.-for melting points below 210 F. than said oxidized asphaltsubstantially the same penetration at 77 F., and a "higher melting pointthan said oxidized asphalt ULRIC B. BRAY. LAWTON B. BECKWITH.

